Acute coronary syndrome - a frequent clinical manifestation of bare metal in-stent restenosis

Abstract

Background: In-stent restenosis (ISR) complicates 20-30% of percutaneous coronary interventions (PCI) with bare metal stent (BMS) implantation. Although the widespread use of drug eluting stents (DES) across Europe caused a considerable reduction of BMS implantations, their number is still lower than the number of BMS implantations in several countries.

Aim: The clinical presentation of ISR has not been well characterissed. Thus, we attempted to analyze this condition and assess the treatment of ISR in everyday clinical practice.

Methods: We searched our database for all cases of bare metal ISR between 1999 and 2007. Follow-up angiography after PCI was not a routine procedure but a clinically driven examination. Clinical presentations of ISR were divided into: stable angina, and acute coronary syndromes (ACS), i.e. unstable angina (UA) and myocardial infarction (MI) (further subdivided into NSTEMI and STEMI). Analysis included variables associated with different clinical manifestations, methods of ISR treatment and in-hospital complications of ISR.

Results: In-stent restenosis was identified in 432 (3%) of 15,910 patients who underwent PCI. The mean age was 61.6 + or - 15.6 (27-86) years, and 295 (68.3%) patients were men. Risk factor distribution was typical for a Caucasian population. Recurrent clinical episode occurred at a mean of 7 (1-108) months after PCI. Exertional angina was present in 245 (56.7%) patients, UA in 128 (29.6%) patients and MI in 59 (13.7%) patients, including STEMI in 28 (6.5%) and NSTEMI in 31 (7.2%) patients. Overall, ACS was diagnosed in 187 patients or 43.3% of all cases of ISR. Multivariate analysis showed a positive correlation between previous MI and younger age and ACS as the clinical manifestation of ISR, and a negative correlation between more severe restenosis and ACS manifestation. The incidence of clinical complications (MI or death) was higher in patients with ACS as the clinical manifestation of ISR (6.9% vs 1.6%).

Conclusions: In-stent restenosis after BMS implantation is a serious clinical problem. More than 40% of patients with ISR present with ACS, including 13.7% patients with MI, more frequently among younger patients and patients with previous MI. Most patients with ISR are treated with repeated PCI with high success rate (97.7%), although the risk of clinical complications is considerably higher in patients presenting with ACS.